William g



(No Model.) v

- W. G. DAVID.

. GALVANOMETBRQ No. 305,431. V PatentedSept. 23, 1884.

a nn 3 NITED STATES PATENT Orrrcs.

\VILLIAM G. DAVID, OF LYONS, NE\V YORK.

GALVANOMETER.

$PECIFICA'1ION forming part ofLetters Patent No. 305,431, dated September 23, 1884. Application filed November 28, 1883. (No model.)

To aZZ whom it may concern: porting the c'oil'in a horizontal position and Be it known that I, WILLIAM G. DAVID, a balancing the needle so that it may lie in the citizen of the United States, and aresident of plane of the coil. To the pivotal center of 5 Lyons, in the county of Wayne and State of the needle I secure alight hollow-pointer pro- 5 New York, have invented certain new and usevided with an adjustable weight, and in the ful Improvements in Galvanometers, of which pointer I inserta pin that may slide in and out the following is a specification, reference beof the pointer in line with its length. The ing had to the drawings accompanying and passage of a current through the coil of this forming a part of the same. instrument causes a deflection of the needle 10 My invention consists in an apparatus for from the horizontal position. The pointer will use in the determination of the strength of in consequence be turned to an angle from the electric currents, and for other-and similar vertical. Below the pointer is a fiat smooth purposes, the general object of the invention surfacc,11p011 which the point of the sliding being to produce an instrument of more sirnpin remains in contact, tracing a straight line 1 ple construction than those heretofore used, from the point, upon which it rests when the and one involving less expense and time in its pointer is inavertical position. The position construction. of the-point of the pin on thisline indicates In carrying out my invention Iconstruct an the tangent of the angle to which the needle 7ov apparatus operating in the manner of an ordiis deflected, and a scale may be readily laid off 20 nary tangent-galvanometer, and in describing to indicate the value of these tangents. This the nature of the same Iwill indicate the parinstrument I use as an ammeter or pressure. ticular features which distinguish it from inindicator for electric circuits, for aregisteringstruments of this class. meter of current strength, or similar purposes.

An ordinary tangent-galvanometer consists In the drawings hereto annexed, Figure 1 25 of a small magnetic needle suspended or is a vertical central section of the apparatus mounted in the center of a comparatively invented by me. Fig. 2 is a perspective illuslarge circle or coil. The instrument is adtrating the devices for recording the deflection justed by setting the coil vertically in the magof the needle. netic meridian, the needle lying in the plane A is a base; B 13, standards, and O a coil of 0 of the coil. Upon the passage of a current any kind, such as ordinarily used in tangentthrough the coil the needle is deflected from galvanometers.

the plane of the coil, the deflection depending D is a 'plate upon which the coil is mounted upon the strength of the current passing, and in a horizontal position. Upon this plate are thetangent of the angle of deflection being set standards E, upon which is mounted, by

35 proportional to the strength of the current. knife-edges, a short bar magnet or needle, F,

In place of depending upon the magnetism of weighted or balanced so as to lie. in a horizonthe earth as the directive force of the needle, tal position.

a magnet. may be employed, which obviates Gis alight tube, of aluminium, for example, 0 the necessity of adj usting'the instrument in attached to the needle F at its center, and exz o the magnetic meridian; but in the instruments lending vertically through a slot in the plate heretofore constructed circular graduated D. Uponthetube G, is asmall sliding weight, scales have been employed, either in conjunc- H, in which is a set-screw, h. tion with the needle itself or with a light K is a light pin inserted in the hollow tube 5 pointer attached thereto; or when these have or-pointer G, and adapted to slide freelytherein.

5 been dispensed with the use of apparatus of On the base A is laid a plate, L, of any maa more complex and expensive character has terial withasmooth surface, uponwhichgradubeen necessitated. The special objects of my ations may be marked. If acurrent be passed invention are, first, to substitute gravity for through the coil 0, the needle is deflected and magnetism as the directive force; and, secondthe tube G moved out of the vertical position.

50 ly, to dispense with the circular scales now in The end of pin K remains in contact with the use. To accomplish thisI mount in the center plate L, the pin sliding out of the tube. The of a coil or coils a short needle or magnet, supdistance from the point at which the pin rests to the startingpoint represents the tangent ol' the angle through which the needle and tube have deflected. It is obvious that a scale may be laid oil on either side of the zero or starting point in a straight line to indicate the value of these tangents.

By substituting for the plate L a traveling band of paper (represented by M) marked off into arbitrary squares the pin may be made to trace a line from which the amount of current that has passed through the circuit in a given time may be readily computed. To ob tain this record the pin may be made partly or wholly of plumbago, or the paper may be chemically prepared and a current passed through it from the pointer.

To adjust the instrument, itis simply necessary to move the weight H up or down until the pin K gives the proper reading for a current of known strength. This means of adjustment makes it an easy and simple matter to adjust or standardize the instruments.

The instrument, though more particularly designed for use with circuits carrying very powerful currents, is nevertheless capable of remarkable accuracy, and may be used generally 'l'orthose purposes to which instruments of this class are commonly applied.

The details of mechanical construction are capable of great variation, particularly with respect to the indication of the tangent by means of the tube or pointer G.

lVithout, theretore, confining mysell'to such details as are here exhibited, what I claim as my invention is- 1. The combination, with a horizontal coil, of a magnet or magnetized needle mounted in the center of the coil, in the plane of the same,

and capable of deflection in a vertical plane only, a pointer attached to said needle, and a rectilinear scale over which the poi n tcr travels, all substantially as herein set forth.

2. The combination, with a horizontal coil, of a magnet or magnetized needle mountedin the center of the coil, in the plane of the same, and capable of deflection .in a vertical plane only, a pointerattached to the needle, and an adjustable weight thereon, substantially as set forth.

3. The combination, with a horizontal coil, of a magnet or magnetized needle mounted in the center of the coil, in theplane of the same, and capable of deflection in a vertical plane only, a tube or hollow pointer attached to the needle, asliding pin within said tube or point-- er, and a scale over which the needle moves, all substantially as set forth.

at. The combination, with a horizontal coil,

of a magnetized needle mounted in the center 0 t the coil, in the plane of the same, a tube attached to the needle, an adjustable weight on the tube, a sliding pin within said tube, and a scale or its equivalent upon which the pin rests, all substantially as set forth.

5. The combination, with a coil 0, of a balanced needle or magnet, F, mounted on knil'eedges in its center, the pointer or tube (t, adjustable weight 111', sliding pin K, and a scale over which the point of said pin moves, as and for the purpose specified.

In testimony whereof I have hereunto set my hand this 23d day of November,

\VIL'LIAM G. DAIVII).

Vitn esses: 

